Reverse pulse cleaning of filter elements

ABSTRACT

An air supply system and valve is disclosed which provides a reverse pulse of air for cleaning a filter element located in a filter house. A valve is also disclosed for use in the air supply system. The system includes a pressure vessel adapted to contain a volume of compressed air to be used for supplying the reverse pulse, the pressure vessel having a wall with at least one outlet aperture therein. The valve is mounted to the wall around the aperture to control the flow of air from the pressure vessel, the valve means comprising a valve body having an inlet, an outlet and a flow passage connecting the inlet and outlet, the inlet, the outlet and the flow passage generally extending axially through the valve body, a valve seat surrounding the flow passage, and a valve closure member movable towards and away from the valve seat into closed and open positions to thereby close or open the flow passage, and operating means for moving the valve closure member between the closed and open positions. A conduit mounted to the valve body around the outlet and adapted to extend into the filter house in use so as to direct a pulse of air towards a filter element to be cleaned when the valve closure member is in the open position.

FIELD OF THE INVENTION

This invention relates to a valve that can be used to control reversepulse cleaning of filter elements and to a reverse pulse cleaning systemthat incorporates such a valve.

BACKGROUND OF THE INVENTION

Reverse pulse cleaning systems are traditionally used to clean bag typefilter elements located in bag houses or the like. In one application,filter bags are suspended from a support plate and are held in an openposition by a wire cage or the like. Air to be cleaned is passed upthrough the filter bags from below the plate through the filter bags andthrough apertures in the plate located at the mouth of the bags. When inuse the filter bags become clogged a reverse pulse of air is dischargedinto the bag through the mouth in the plate. That pulse serves toprovide an energy wave, which flexes the filter bag, resulting inparticulate material which has adhered to the bag during the filteringprocess being dislodged from the bag and falling to a hopper in thebottom of the bag house.

Prior art systems have tended to use high-pressure low volume reversepulses of air to clean the filter bags. However, high-pressure systemstend to be costly to operate and maintain, and also tend to be noisy inoperation.

SUMMARY OF THE INVENTION

According to a broad aspect of the invention, there is provided an airsupply system adapted to provide a reverse pulse of air for cleaning afilter element located in a filter house, said system comprising:

-   -   a pressure vessel adapted to contain a volume of compressed air        to be used for supplying said reverse pulse, said pressure        vessel having a wall with at least one outlet aperture therein;    -   valve means mounted to said wall around said aperture to control        the flow of air from said pressure vessel, said valve means        comprising a valve body having an inlet, an outlet and a flow        passage connecting the inlet and outlet, said inlet, said outlet        and said flow passage generally extending axially through said        valve body, a valve seat surrounding said flow passage, and a        valve closure member movable towards and away from said valve        seat into closed and open positions to thereby close or open        said flow passage, and operating means for moving said valve        closure member between said closed and open positions; and    -   a conduit mounted to said valve body around said outlet and        adapted to extend into said filter house in use so as to direct        a pulse of air towards a filter element to be cleaned when said        valve closure member is in said open position.

The inlet and outlet may be in general axial alignment with one another.

The valve means may further comprise engagement formations adapted toengage said at least one outlet aperture of said pressure vessel,wherein said valve is at least partially within said pressure vessel.

Optionally, the pressure vessel has a volume which exceeds the volume ofair required for a reverse pulse of the system.

Advantageously, the pressure vessel may be a low-pressure system adaptedto contain pressure at between 100 and 300 kPa and may contain pressureat between 120 kPa and 150 kPa Furthermore, the pressure vessel may havea circular cylindrical configuration and said aperture may have an axisperpendicular to the cylinder axis.

Optionally, the valve body has a mounting flange or shoulder on an outersurface thereof shaped and configured to engage and seal with the outersurface of the pressure vessel surrounding said aperture. The valvemeans may further comprise a clamp arrangement mounted thereto adaptedto clamp the valve body to the pressure vessel by engagement with aninner surface of the pressure vessel. Optionally, the clamp arrangementis operable from a position exterior of the pressure vessel such thatthe valve body can be mounted to, or removed from, the pressure vesselfrom said exterior position. Typically, the clamp arrangement comprisesa substantially C-shaped clamp which is in engagement with a bolt whichextends axially through the body, rotation of the bolt causing theC-shaped clamp to move towards and away from the body.

The valve may include an internally threaded coupling member adapted tobe located within an outlet aperture to engage an inner surface of thepressure vessel, the valve body in use being secured into the couplingmember, including engagement formations adapted to engage an innersurface of the pressure vessel, the valve body in use being secured intothe coupling member to cause said engagement formations to operativelyengage the inner surface to thereby mount the valve to the pressurevessel.

The valve closure member may include a poppet type valve closure member.

Optionally, the valve closure member is spring biased into a closedposition.

The poppet type valve closure member may be axially mounted to a stemhaving a piston on the distal end thereof, the piston being located inand slideable relative to a cylinder which is fixed relative to andaxially aligned with the valve body, said valve closure member beingmoveable by varying the pressure within said cylinder.

The pressure chamber may be located on and aligned with the valve axis.

The body may include turbulent air flow reducing means in the locationof the outlet, said turbulent air flow reducing means being adapted toreduce turbulent flow of air within said outlet in use. The turbulentair flow reducing means may include a shroud or cowl shaped extension onthe outlet side of the valve.

The conduit may have a constricted end which will serve to increase thevelocity of air flow at the outlet.

The system may further comprise a tubular bracket for mounting theconduit as it passes through a wall of a filter house, the tubularbracket comprising an elongate tubular body having an internal wallsized to be a close sliding fit with the external surface of theconduit, the tubular body having an external thread thereon adapted toreceive a nut for clamping the bracket to a filter house wall in arelatively rigid arrangement. The tubular body may have a plurality oftapered catches thereon which are biased outwardly but which have thecapacity to flex resiliently inwardly as said bracket is inserted intoan aperture through a wall of a filter house, and flex outwardly whenthe tubular bracket is in position to hold the tubular bracket inposition.

The valve body may be adapted to be coupled to a coupling ring orannular flange for coupling the valve to the pressure vessel, the flangeor coupling ring including means for engaging with the pressure vessel,and the valve body including formations adapted to engage withco-operant formations on the flange or coupling ring to mount the valvebody to the flange to coupling ring.

Another broad aspect of the invention provides a valve comprising:

-   -   a valve body having an inlet, an outlet, and a flow passage        connecting the inlet and outlet, said inlet, said outlet and        said flow passage generally extending axially through said valve        body;    -   a valve seat surrounding the flow passage and a valve closure        member moveable towards and away from the valve seat to close        and open the valve respectively, and the valve closure member        comprising:    -   a poppet-type closure member axially mounted to a stem having a        piston on the distal end thereof, the piston being located in        and slideable relative to a cylinder which is fixed relative to        the valve body, said valve closure member being moveable by        varying the pressure within said cylinder.

The inlet and outlet may be in general axial alignment with one another.The valve optionally further comprises engagement formations adapted toengage a wall of a pressure vessel or conduit in use to thereby mountsaid valve body to said wall in use. The engagement formations maycomprise:

-   -   a rod extending through said valve body, said stem, said piston        and said valve closure member, said rod being in general axial        alignment with said valve body; and    -   a clamp arrangement mounted to said rod, said clamp arrangement        being adapted to clamp said valve to a pressure vessel by        engagement with an inner surface of said vessel.

The valve may further comprise a biasing means to bias said valveclosure member toward said valve seat. The biasing means may include aspring provided on said rod and located between said clamp and saidvalve closure member.

The clamp arrangement optionally comprises a generally C-shaped clampwhich is in threaded engagement with a threaded end of said rod, whereinrotation of said rod causes said generally C-shaped clamp to move towardand away from said valve body.

The valve body may include turbulent flow reducing means in the locationof said outlet, said turbulent flow reducing means being adapted toreduce turbulent flow of fluid within said outlet in use.Advantageously, the turbulent flow reducing means reduces the turbulentflow of fluid within said outlet in use, thereby reducing the noiseassociated with the flow of air through the valve. The turbulent flowreducing means may include a shroud or cowl shaped extension on theoutlet side of the valve body.

Advantageously, the valve includes a pilot conduit extending throughsaid valve body into said cylinder, said pilot conduit adapted to beconnected to a source of high pressure fluid for increasing the fluidpressure in said conduit to move said valve closure member away fromsaid valve seat and thereby open said valve.

Preferably, release of said source of high pressure fluid from saidpilot conduit decreases the fluid pressure in said conduit to cause saidbiasing means to bias said valve closure member toward said valve seatand thereby close said valve.

A bleed conduit may extend through said piston from said cylinder tosaid flow passage to allow fluid under pressure in said cylinder todischarge into said flow passage upon release of said source of highpressure fluid. The generally C-shaped clamp may be adapted to clamp toan internal wall of a pressure vessel or a conduit for supplying areverse pulse of air for reverse pulse cleaning of filter elements.

The outlet may be connected to a conduit adapted to direct a pulse ofair toward one or more filter elements to be cleaned when said valve isopen.

The valve body may be adapted to be coupled to a coupling ring orannular flange for coupling the valve to a pressure vessel, the annularflange or coupling ring including means for engaging with the pressurevessel, and the valve body includes formations adapted to engage withco-operant formations on the flange or coupling ring to mount the valvebody to the flange to coupling ring.

According to yet a further broad aspect of the invention, there isprovided a method of cleaning a filter element using a source ofpressurised air, said source of pressurised air being supplied to aconduit adapted to extend into a filter house that houses said filterelement, said conduit being connectable to said source of pressurisedair by a valve, said valve comprising a valve body having an inlet, anoutlet, and a flow passage connecting the inlet and outlet, said inlet,said inlet, said outlet and said flow passage generally extendingaxially through said valve body; a valve seat surrounding said flowpassage, and a valve closure member movable towards and away from saidvalve seat into closed and open positions to thereby respectively closeor open said flow passage, and operating means for moving said valveclosure member between said closed and open positions, said outlet ofsaid valve body being mounted to said conduit that extends into saidfilter, said method comprising the step of:

-   -   actuating said operating means to move said valve closure member        to said open position to introduce a high volume, low pressure        reverse pulse of air into said filter element.

The inlet and outlet may be in general axial alignment with one another.

The pulse of air is optionally provided at a pressure of between 100 and300 kPa and the volume of the pulse of air may be between 50 l and 100l.

These and further features of the invention will be made apparent fromthe description of preferred embodiments thereof given below by way ofexamples. In the description reference is made to the accompanyingdrawings but the specific features shown in the drawings should not beconstrued as limiting on the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described by way ofthe following non-limiting example, with reference to the accompanyingdrawings:

FIG. 1 shows a rear view of a reverse pulse cleaning system whichemploys four reverse pulse valves;

FIG. 2 shows a side view of the system shown in FIG. 1;

FIG. 3 shows a plan sectional view along line III-III shown in FIG. 1;

FIG. 4 shows a perspective view of a first embodiment of outlet valvefor the system shown in FIGS. 1 to 3;

FIG. 5 shows a cross sectional side view of the valve shown in FIG. 4;

FIG. 6 shows a cross sectional plan view of a system similar to thatshown in FIG. 1 to 3 with a conduit attached to the valve which in turnpasses through a wall of a filter house;

FIG. 7 shows a perspective view of a third embodiment of valve with theconduit attached thereto;

FIG. 8 shows a cross sectional side view of the valve shown in FIG. 7;

FIG. 9 shows a cross sectional side view of a fourth embodiment of valvemounted to a pressure vessel via a two part coupling ring;

FIG. 10 shows the inner part of the coupling ring for use in mountingthe valve of FIG. 9 to the pressure vessel;

FIG. 11 shows the valve of FIG. 9 without the coupling ring locatedthereon;

FIG. 12 show the inner and outer parts of the coupling ring together;

FIG. 13 shows a perspective view of an alternative mounting arrangementin the form of a flange mounting assembly for mounting the valve of FIG.9 to the pressure vessel;

FIG. 14 shows a perspective exploded view of the mounting arrangement ofFIG. 13;

FIG. 15 shows the mounting arrangement of FIG. 13 from a top view;

FIG. 16 shows a cross-sectional view the line A-A of FIG. 15;

FIG. 17 shows a perspective view of the mounting arrangement of FIG. 13mounted to a pressure vessel; and

FIG. 18 shows a cross-sectional view of FIG. 17.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIGS. 1 to 3, a reverse pulse cleaning system 10 includes apressure vessel 12 of generally right circular cylindrical configurationhaving an inlet for air under pressure (not shown) and four outlets 14.Each of the outlets 14 is controlled by respective valve 16 which leadsinto an outlet conduit 18. The conduits 18 are configured to passthrough a wall of a filter house (not shown) and are configured andaligned so as to ensure that an air pulse passing out of the conduits 18is correctly oriented with the mouth of a filter element to be cleaned.It will be noted, particularly in FIG. 2 that the conduits 18 slopedownwardly at angle of approximately 15° since this is the angle atwhich the filter elements are aligned within the bag house in theembodiment disclosed herein. However, of course, with a different filterhouse configuration, different conduit shapes and length will berequired, and the orientation of the conduits 18 will need to be alignedwith the filter elements.

Each of the valves 16 is operated by a separate high pressure pilotconduit which applies high pressure fluid for opening the valves in use.The valves will be opened either at regular intervals, or when theirrespective filter elements into which they will direct a reverse pulseare clogged to the extent to where they require cleaning. A controlsystem (not shown) will be used to open the respective valves 16 inaccordance with a predetermined operating arrangement which does notform part of this invention. However, as will be clear from thedescription which follows here below, a system of opening the valves inaccordance with their required operating protocol is required for asystem to operate.

As will be clear from FIG. 3, the valves 16 are mounted to the wall ofthe vessel 12 in such a manner that the valves can be removed from thevessel 12 from a position exterior of the vessel 12. Also, the vessel 12does not need to be dismounted in order for individual valves to beremoved. The valves 16 are provided with internal mounting brackets 20which hold the valves 16 firmly against the vessel 12. The brackets 20are each in the form of a generally c-shaped bridge clamp which is heldin position by a threaded rod 22 which is used to tighten the bridgeclamp 20 against the inner surface of the vessel 12. These aspects willbe described in more detail below.

It will also be noted from FIG. 3 that the valves 16 are configured suchthat the inlet to the valve and outlet from the valve are axiallyaligned. This is to ensure there is a minimum pressure drop across thevalve when the valve is open which is important to achieve efficientoperation of the system. The flow passage through the valve is also ofrelatively high capacity, with minimal components in the flow passage tointerrupt air flow when the valve is open.

The vessel 12 is of relatively large capacity and in the embodimentshown is of approximately 80 litres volume. The vessel is intended to bea relatively low pressure vessel, that is the vessel is designed towithstand an internal pressure of between 100 and 160 kPa, preferablyapproximately 130 kPa. Typical reverse pulse cleaning systems operate atfar higher pressures, often up to approximately 800 kPa but for thereasons mentioned above, including noise of operation, a low pressuresystem is preferable to provide efficient cleaning of filter elementsover a high pressure system.

Turning now to FIGS. 4 and 5, a valve 16 of the type which is suitablefor use with the system depicted in FIGS. 1 to 3 is shown in moredetail. As shown, the valve 16 includes a valve body 24 which is ofgenerally tubular configuration and has an inlet 26 and outlet 28coaxially aligned with the inlet 26. A flow passage 30 extends betweenthe inlet and the outlet and a valve seat 32 surrounds the flow passage.As shown by the dashed line A-A, which shows the axis of the valve body24, the inlet 26, outlet 28 and flow passage 30 extend axially throughthe valve body 24 and the inlet 26 and outlet 28 are in general axialalignment with one another.

A poppet type valve closure member 34 is moveable towards and away fromthe valve seat in order to close and open the valve. The poppet typevalve closure member 34 is slideable on a rod 36 which lies on the valveaxis and is supported in a central boss 38 which is connected to thevalve body 24 via a web 40. The boss 38 defines a pressure chamber 42and the valve closure member 34 includes a piston 44 on its distal endwhich locates within the pressure chamber 42, the pressure chamber 42thus serving as a cylinder. A high-pressure fluid supply line 46 extendsthrough the web 40 into the pressure chamber 42, and high-pressure fluidpassing through the passage 46 into the cylinder 42 will cause the valve34 to open. A compression spring 48 biases the valve into a closedposition.

A recess is provided adjacent to the piston 44 to allow a seal 47 to belocated around the body the piston to seal the piston and the inner wallof the chamber 42. Another recess is provided in the piston 44 to allowa seal 43 to seal between the piston 44 and the rod 32.

Thus, the valve 16 will typically be in a closed position under theinfluence of the compression spring 48, but when it is necessary to openthe valve a high-pressure line connected into passage 46 will opened topressurise the pressure chamber 42 and open the valve. A small diameterbleed conduit (not shown in the drawings) extends through the piston 44,between the chamber 42 and the flow passage 30 to allow fluid to releaseform the chamber 42 when high pressure air is not being supplied topassage 46 to thereby reduce the pressure in the chamber 42. In thisembodiment, the internal diameter of the bleed conduit is 1.22 mm andthe internal diameter of the passage 46 is 2.5 mm, so that pressure canbuild up in chamber 42 when the valve closure member is in the openposition.

It will be noted that when the valve closure member 34 is in its openposition, as shown, the valve 16 defines a relatively straight flowthrough passage, which will result in a very low pressure drop acrossthe valve. Thus, when the valve is open, substantially the entirecontent of air under pressure in the pressure vessel 12 will dischargevery rapidly through the open valve, down conduit 18, to the filterelement. Hence, it will be appreciated that the valve 16, when in itsopen position provides a very efficient valve in that it minimisespressure drop from the pressure vessel 12 to the conduit 18 due to theinlet 26, flow passage 30 and outlet 28 being generally axially aligned.Furthermore, the reduced pressure drop as air passes through valve 16also provides the advantage of reducing noise associated with therelease of air under pressure in the pressure vessel 12. Hence, thevalve 16 can be used to reduce noise associated with reverse pulse aircleaning systems, which is highly desirable in promoting reduced noiseworking environments.

It will also be appreciated that the valve closure member 34 could beused in applications other than in reverse pulse cleaning systems,particularly in applications where it is desirable to use a valve thatprovides a reduced pressure drop of fluid upon opening the valve.

The bridge clamp 20 is shown in more detail in FIG. 4 of the drawings.It will be noted that the bridge clamp 20 is of substantially C-shapedconfiguration and the rod 36, which is screw threaded on its distal end,screws into the bridge clamp 20. Rotation of the rod 36 will cause thebridge clamp 20 to move towards the inner surface of the pressure vessel12 to thereby clamp the valve against the outer surface of the pressurevessel.

It will be noted that the valve body 24 includes a saddle shaped sealingsurface 50 which will seal against the outer surface of the pressurevessel 12 when the valve is tightly clamped against the pressure vessel.This will eliminated any air leakage out of the pressure vessel 12 whenthe valve is closed.

It will be noted that the conduit 18 has a reduced diameter outlet end52 which will increase the velocity of air leaving the conduit and theoutlet region, thereby increasing the efficiency of the pulse air to beused to clean the filter element. The end 52 might have a configurationwhich differs from that depicted in the drawings, depending on thenature of the filter element to be cleaned, and the desired exitvelocity of the reverse pulse of air.

Turning to FIG. 6 of the drawings it will be noted that a conduit 18 isshown passing through a wall 54 of a bag house or filter house. Itshould be noted that reference numerals have been omitted from some ofthe features in FIG. 6 for clarity. The conduit 18 passes through thewall 54 and is supported by a tubular bracket 56 which provides supportfor the conduit 18 and perpendicular alignment with the wall 54. Thetubular bracket 56 includes a tubular body 58, an outer end of which isscrew threaded as indicated at numeral 60, and a union nut 62 securesthe tubular bracket in position and clamps the bracket around theconduit 18. When in position, the bracket will ensure that the conduit18 is correctly aligned with the filter elements located within the baghouse.

It will also be noted that the vessel 12 is supported on the wall 54 viaa bracket 64, the bracket 64 including a nut and bolt assembly 66 whichensures the bracket 64 is properly clamped around the vessel 12, and abolt 68 which secure the bracket 64 and hence the vessel 12, to the wall54.

A clip 70 is used to secure the conduit 18 to the valve 16, the conduit18 locating within an outlet region of the valve 16. In the embodimentsshown in the FIGS. 4 and 5, the conduit 18 is held to the valve 16 via aunion nut 72.

It will be clear from FIG. 6 that one of the advantages of the valveused with the system is that it is possible to remove the valve 16 fromthe vessel 12 without removing the vessel 12 from position. In order toremove the valve, for maintenance, repair or other purposes, the clip 70will be removed from the conduit 18 and the union nut 72 removed fromthe bracket 56. This will allow the conduit to be rotated away from thevalve 16 which in turn will expose the hexagonal head 78 of the rod 36.Rotation of the rod 36 using a suitable tool applied to the hexagonalhead 78 will cause the bracket 20 to come out of contact within a wallof the vessel 12. Once the valve and bracket become loose this could bea simple matter to manipulate the valve so as to extract the portions ofthe valve located within the vessel 12, including the bracket 20, fromthe interior of the vessel 12. This ability to allow for quickdisengagement of the valve 16 from the vessel 12 is considered to be asignificant advantage of the assemblies described herein.

The valve shown in FIGS. 7 and 8 of the drawings (it should be notedthat reference numerals have been omitted from some of the features inFIG. 7 and FIG. 8 for clarity) is similar to that of the previousembodiment except that the seat 80 which is adapted to engage againstthe outer surface of the vessel 12 is set back from the inlet end of thevalve body. This will ensure that a significant portion of the valvebody is located within the vessel 12 when the valve is operativelymounted to a vessel 12. By mounting the valve in this way, only a smallportion of the valve body will project out of the vessel 12, and thiswill allow more space for the conduit 18 to fit with particularcomplicated configurations of bag house with which the system is to beused. Where the seat 80 is set back, as shown in FIGS. 7 and 8, the arms32 of the bridge clamp 20 will need to be longer than the arms shown inFIG. 4 of the drawings.

Clearly the seat 80 needs to be configured so as to seal with the outersurface of the vessel 12. Where the vessel 12 is of rectangular shape,for example the seat 80 will not need to be saddle shaped but could inthat instance, be perpendicular to the valve axis.

Turning now to the valve shown in FIGS. 9 to 12 of the drawings, it willbe noted that the valve shown adopts a different method of coupling thevalve to the pressure vessel, but the valve is still able to be mountedto and removed from the vessel from a position exterior of the pressurevessel. In this embodiment the valve uses a coupling ring 82 to connectthe valve body to the pressure vessel 12. In the drawings for clarityreasons the valve is shown without the poppet type valve closure membermounted thereto.

As shown, the valve 84 comprises a valve body 86 having screw threads 88formed around the inlet end 90 thereof, and screw threads 92 formed onthe outlet end thereof for mounting a conduit thereto.

The coupling ring 82 is adapted to be mounted to the pressure vesselfirst, and the valve body is then screwed into the coupling ring in themanner described below. The coupling ring comprises an inner ring 94 andan outer ring 96. The inner ring 94 has four integral fingers 98 whichproject forwardly, that is, into the pressure vessel when the couplingring is operatively mounted to a pressure vessel. The fingers 98 areflexible and have outwardly projecting shoulders 100 thereon adapted tolocate within the pressure vessel and engage with the inner surface ofthe pressure vessel to securely mount the valve to the pressure vessel.The shoulders 100 have forward and rearward facing tapered surfaces 102to allow the inner ring to be pressed into and removed from the outletaperture in the pressure vessel.

The inner ring 94 is internally threaded with threads 95 configured toengage with the threads 88 on the valve body. The inner ring 94 includesa spline 104 on the outer surface thereof aligned with the valve axisand adapted to locate within one of two slots 106 formed in the innersurface of the outer ring 96 which will allow the two rings to slideaxially relative to each other.

The outer ring 96 has a saddle shaped forward facing surface 108 adaptedto seat against and seal with the outer surface of the pressure vessel12. To mount the valve 84 to the pressure vessel firstly an aperture ofdiameter which matches the outer diameter of the inner ring will bebored into the wall of the pressure vessel. A small slot will also beformed at the appropriate position in the edge of that aperture toreceive the spline 104. This will ensure the saddle shaped surface 108is correctly aligned with the outer surface of the pressure vessel.

The inner ring will then be pushed into the aperture, causing thefingers 98 to flex inwardly until the shoulders 100 have moved past thewall of the pressure vessel into the interior of the vessel. Thereafterthe outer ring will be located around the rearward end of the innerring, and the valve body will be screwed into the threads 95. The valvebody has a forward facing neck portion 110 on its inlet end whichdefines the valve seat for the poppet valve closure member. The fingers98 have a radially inner surface 112 which is tapered as shown in FIG.9, and projects slightly into the path of the neck portion 110 so thatwhen the valve body is screwed fully into the coupling ring the neckportion 110 will engage the inner surfaces 112 of the four fingers andurge the fingers outwardly into engagement with the pressure vessel,thereby locking the shoulders 100 against the inner surface of thepressure vessel.

The valve body has a forward facing shoulder 114 which presses againstthe rearward face 116 of the outer ring. When the valve body is screwedfully into the inner ring the shoulder 114 will press against the face116 pressing the outer ring hard against the outer surface of thepressure vessel. Seals, typically O-ring seals (not shown) will belocated in the surfaces 108 and 116 to ensure that no leakage out of thevalve will take place around the edge of the valve.

To remove the valve from the pressure vessel the valve will simply beunscrewed. With the valve out of engagement with the fingers the fingerswill be free to flex inwardly so that the coupling ring can be removedfrom the pressure vessel if necessary. The coupling ring thus serves asa relatively simple connection arrangement which allows for mounting ofthe valve from a position exterior of the pressure vessel, and alsoallows for rapid replacement of the valve for maintenance or repairpurposes.

This ability to replace valves quickly can be important. With many priorart systems, valve replacement can involve lengthy and complexdisassembly of the whole cleaning system, resulting in lengthyinterruption of the plant in which the filter house is located. With thepresent system, valve replacement can be done in a matter of minuteswithout specialist personnel.

Referring now to FIG. 13, there is shown yet another alternativeassembly 120 for coupling valve 84′ to the pressure vessel 12′. Thefeatures of valve 84′ are similar to those described for valve 84 andhence, similar features will be marked with the same reference numeralincluding the quotation mark (′) for convenience and the description ofthose features will not be repeated.

FIG. 14 shows a rear perspective exploded view of the mountingarrangement 120 of FIG. 13; FIG. 15 shows the mounting arrangement 120of FIG. 13 from a top view; and FIG. 16 shows a cross-sectional view theline A-A of FIG. 15. FIG. 17 shows a perspective view of the mountingarrangement of FIG. 13 mounted to a pressure vessel 12′; and FIG. 18shows a cross-sectional view of FIG. 17. It should be noted thatreference numerals have been omitted from some of the features in FIG.17 and FIG. 18 for clarity.

The valve 84′ includes valve body 86′ which includes a flange 122 thatis generally square shaped in top view and which extends outwardly fromthe flange body 86′. At each corner of the flange 122, attachment boresextend through the body of the flange 122 to allow bolts 126 to beinserted therein and allow the flange 122 to be attached to a plate 130attached to pressure vessel 12′ as shown in FIG. 17 and FIG. 18.

Washers 127 are also provided between the head of the bolt 124 and theflange 122 to provide a seat for the bolt head and ensure goodattachment between the flange 122 and plate 130.

In installation, the flange 122 is connected the plate 130 by drillingholes through the plate 130 such that the attachment bores are alignedwith the holes 125 of the flange 122. The flange 122 is connected to theplate 130 by inserting the bolts 124 through the attachment holes andfastening the bolts 124 using threaded nuts (not shown). The plate 130is attached to the pressure vessel 12′.

It will be understood that the invention disclosed and defined hereinextends to all alternative combinations of two or more of the individualfeatures mentioned or evident from the text or drawings. All of thesedifferent combinations constitute various alternative aspects of theinvention.

The foregoing describes embodiments of the present invention andmodifications, obvious to those skilled in the art can be made thereto,without departing from the scope of the present invention.

1. An air supply system adapted to provide a reverse pulse of air forcleaning a filter element located in a filter house, said systemcomprising: a pressure vessel adapted to contain a volume of compressedair to be used for supplying said reverse pulse, said pressure vesselhaving a wall with at least one outlet aperture therein; valve meansmounted to said wall around said aperture to control the flow of airfrom said pressure vessel, said valve means comprising a valve bodyhaving an inlet, an outlet and a flow passage connecting the inlet andoutlet, said inlet, said outlet and said flow passage generallyextending axially through said valve body, a valve seat surrounding saidflow passage, and a valve closure member movable towards and away fromsaid valve seat into closed and open positions to thereby close or opensaid flow passage, and operating means for moving said valve closuremember between said closed and open positions; and a conduit mounted tosaid valve body around said outlet and adapted to extend into saidfilter house in use so as to direct a pulse of air towards a filterelement to be cleaned when said valve closure member is in said openposition.
 2. An air supply system according to claim 1, wherein theinlet and outlet are in general axial alignment with one another.
 3. Anair supply system according to claim 1 or claim 2, wherein the valvemeans further comprises engagement formations adapted to engage said atleast one outlet aperture of said pressure vessel, wherein said valve isat least partially within said pressure vessel.
 4. An air supply systemaccording to any one of claims 1 or 2, wherein the pressure vessel has avolume which exceeds the volume of air required for a reverse pulse ofthe system.
 5. An air supply system according to any one of claims 1 or2, wherein the pressure vessel is a low-pressure system adapted tocontain pressure at between 100 and 300 kPa.
 6. An air supply systemaccording to claim 5, wherein the pressure vessel is adapted to containpressure at between 120 kPa and 150 kPa.
 7. An air supply systemaccording to any one of claims 1 or 2, wherein said pressure vessel isof right circular cylindrical configuration and said aperture has anaxis perpendicular to the cylinder axis.
 8. An air supply systemaccording to any one of claims 1 or 2, wherein the valve body has amounting flange or shoulder on an outer surface thereof shaped andconfigured to engage and seal with the outer surface of the pressurevessel surrounding said aperture.
 9. An air supply system according toclaim 8, wherein the valve means further comprises a clamp arrangementmounted thereto adapted to clamp the valve body to the pressure vesselby engagement with an inner surface of the pressure vessel.
 10. An airsupply system according to claim 9, wherein the clamp arrangement isoperable from a position exterior of the pressure vessel such that thevalve body can be mounted to, or removed from, the pressure vessel fromsaid exterior position.
 11. An air supply system according to claim 10,wherein the clamp arrangement comprises a substantially C-shaped clampwhich is in engagement with a bolt which extends axially through thebody, rotation of the bolt causing the C-shaped clamp to move towardsand away from the body.
 12. An air supply system according to claim 8,wherein the valve includes an internally threaded coupling memberadapted to be located within an outlet aperture to engage an innersurface of the pressure vessel, the valve body in use being secured intothe coupling member, including engagement formations adapted to engagean inner surface of the pressure vessel, the valve body in use beingsecured into the coupling member to cause said engagement formations tooperatively engage the inner surface to thereby mount the valve to thepressure vessel.
 13. An air supply system according to claim 8, whereinthe valve closure member includes a poppet type valve closure member.14. An air supply system according to claim 13, wherein the valveclosure member is spring biased into a closed position.
 15. An airsupply system according to claim 13, wherein the poppet type valveclosure member is axially mounted to a stem having a piston on thedistal end thereof, the piston being located in and slideable relativeto a cylinder which is fixed relative to and axially aligned with thevalve body, said valve closure member being moveable by varying thepressure within said cylinder.
 16. An air supply system according toclaim 15, wherein the pressure chamber is located on and aligned withthe valve axis.
 17. An air supply system according to claim 13, whereinthe body includes turbulent air flow reducing means in the location ofthe outlet, said turbulent air flow reducing means being adapted toreduce turbulent flow of air within said outlet in use.
 18. An airsupply system according to claim 17, wherein the turbulent air flowreducing means includes a shroud or cowl shaped extension on the outletside of the pressure chamber.
 19. An air supply system according toclaims 1 or 2, wherein the conduit has a constricted end which willserve to increase the velocity of air flow at the outlet.
 20. An airsupply system according to claims 1 or 2, further comprising a tubularbracket for mounting the conduit as it passes through a wall of a filterhouse, the tubular bracket comprising an elongate tubular body having aninternal wall sized to be a close sliding fit with the external surfaceof the conduit, the tubular body having an external thread thereonadapted to receive a nut for clamping the bracket to a filter house wallin a relatively rigid arrangement.
 21. An air supply system according toclaim 20, wherein the tubular body has a plurality of tapered catchesthereon which are biased outwardly but which have the capacity to flexresiliently inwardly as said bracket is inserted into an aperturethrough a wall of a filter house, and flex outwardly when the tubularbracket is in position to hold the tubular bracket in position.
 22. Anair supply system according to claims 1 or 2, wherein the valve body isadapted to be coupled to a coupling ring or annular flange for couplingthe valve to the pressure vessel, the flange or coupling ring includingmeans for engaging with the pressure vessel, and the valve bodyincluding formations adapted to engage with co-operant formations on theflange or coupling ring to mount the valve body to the flange tocoupling ring.
 23. A valve comprising: a valve body having an inlet, anoutlet, and a flow passage connecting the inlet and outlet, said inlet,said outlet and said flow passage generally extending axially throughsaid valve body; a valve seat surrounding the flow passage and a valveclosure member moveable towards and away from the valve seat to closeand open the valve respectively, and the valve closure membercomprising: a poppet-type closure member axially mounted to a stemhaving a piston on the distal end thereof, the piston being located inand slideable relative to a cylinder which is fixed relative to thevalve body, said valve closure member being moveable by varying thepressure within said cylinder.
 24. A valve as claimed in claim 23,wherein the inlet and outlet are in general axial alignment with oneanother.
 25. A valve according to claim 23 or claim 24, furthercomprising engagement formations adapted to engage a wall of a pressurevessel or conduit in use to thereby mount said valve body to said wallin use.
 26. A valve according to claim 25, where the engagementformations comprise a rod extending through said valve body, said stem,said piston and said valve closure member, said rod being in generalaxial alignment with said valve body; and a clamp arrangement mounted tosaid rod, said clamp arrangement being adapted to clamp said valve to apressure vessel by engagement with an inner surface of said vessel. 27.A valve according to claims 23 or 24, further comprising a biasing meansto bias said valve closure member toward said valve seat.
 28. A valveaccording to claim 27, wherein the biasing means includes a springprovided on said rod and located between said clamp and said valveclosure member.
 29. A valve according to claim 26, wherein the clamparrangement comprises a generally C-shaped clamp which is in threadedengagement with a threaded end of said rod, wherein rotation of said rodcauses said generally C shaped clamp to move toward and away from saidvalve body.
 30. A valve according to any one of claims 23 or 24, whereinthe valve body includes turbulent flow reducing means in the location ofsaid outlet, said turbulent flow reducing means being adapted to reduceturbulent flow of fluid within said outlet in use.
 31. A valve accordingto claim 30, wherein the turbulent flow reducing means includes a shroudor cowl shaped extension on the outlet side of the valve body.
 32. Avalve according to any one of claims 23 or 24, further comprising: apilot conduit extending through said valve body into said cylinder, saidpilot conduit adapted to be connected to a source of high pressure fluidfor increasing the fluid pressure in said conduit to move said valveclosure member away from said valve seat and thereby open said valve.33. A valve according to claim 32, wherein release of said source ofhigh pressure fluid from said pilot conduit decreases the fluid pressurein said conduit to cause said biasing means to bias said valve closuremember toward said valve seat and thereby close said valve.
 34. A valveaccording to claim 33, wherein a bleed conduit extends through saidpiston from said cylinder to said flow passage to allow fluid underpressure in said cylinder to discharge into said flow passage uponrelease of said source of high pressure fluid.
 35. A valve according toclaim 29, wherein the generally C shaped clamp is adapted to clamp to aninternal wall of a pressure vessel or a conduit for supplying a reversepulse of air for reverse pulse cleaning of filter elements.
 36. A valveaccording to any one of claims 23 or 24, wherein the outlet is connectedto a conduit adapted to direct a pulse of air toward one or more filterelements to be cleaned when said valve is open.
 37. A valve according toany one of claims 23 or 24, wherein the valve body is adapted to becoupled to a coupling ring or annular flange for coupling the valve to apressure vessel, the annular flange or coupling ring including means forengaging with the pressure vessel, and the valve body includesformations adapted to engage with co-operant formations on the flange orcoupling ring to mount the valve body to the flange to coupling ring.38. A method of cleaning a filter element using a source of pressurisedair, said source of pressurised air being supplied to a conduit adaptedto extend into a filter house that houses said filter element, saidconduit being connectable to said source of pressurised air by a valve,said valve comprising a valve body having an inlet, an outlet, and aflow passage connecting the inlet and outlet, said inlet, said inlet,said outlet and said flow passage generally extending axially throughsaid valve body; a valve seat surrounding said flow passage, and a valveclosure member movable towards and away from said valve seat into closedand open positions to thereby respectively close or open said flowpassage, and operating means for moving said valve closure memberbetween said closed and open positions, said outlet of said valve bodybeing mounted to said conduit that extends into said filter, said methodcomprising the step of: actuating said operating means to move saidvalve closure member to said open position to introduce a high volume,low pressure reverse pulse of air into said filter element.
 39. A methodaccording to claim 38, wherein the inlet and outlet are in general axialalignment with one another.
 40. A method according to claim 38 or claim39, wherein the pulse of air is provided at a pressure of between 100and 300 kPa.
 41. A method according to claim 38 or 39, wherein thevolume of the pulse of air is between 50 l and 100 l. 42-43. (canceled)